Moreno spoke Friday after a 12-hour deadline ended with the captors failing to meet his demands they demonstrate the hostages were still alive or face a military strike.
He stressed that "beyond the efforts we have made, it has been confirmed that these criminals appear to never have had the will to deliver them safe and sound, and it is very likely that all what they wanted was to buy time".
Journalists Javier Ortega and Paul Rivas, along with their driver, Efrain Segarra, were kidnapped last month near the border while on assignment. On Wednesday, the Oliver Sinisterra Front, a faction of the former Revolutionary Armed Forces of Colombia (FARC) guerrillas, which is active in Ecuador, stated that the hostages had been killed during an army's operation in the area.
The International Committee of the Red Cross said in a statement from Bogota that it had received approval from the two governments as well as members of Guacho's groups to organize a humanitarian mission to recover the bodies.
Late Thursday, a visibly emotional Moreno had issued an ultimatum to the kidnappers after his government received photos from a Colombian TV station suggesting the three were dead.
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Moreno returned to Ecuador's capital, Quito, late Thursday, after making an early departure from the Summit of the Americas in Lima, Peru to deal with the situation.
"We have information that confirms murder of our compatriots".
As Moreno spoke, dozens of colleagues and friends of reporter Javier Ortega, photographer Paul Rivas and their driver Efrain Segarra gathered in tears in a plaza outside the presidential palace under the slogan "Three Are Missing", the same one that has featured in candlelight vigils held nearly every night since their disappearance.
"We have already started operations on the Colombian side of the border as they have in Ecuador", he said, while insisting the abduction "happened in Ecuador" and was led by an Ecuadoran national.
The larger FARC movement reached a historic peace agreement with the Colombian government in 2016.
Earlier this week, authorities dismissed as fake a statement in which a group claiming to be a holdout faction of Colombia's demobilized FARC rebel group said the news workers were killed during a military raid. Moreno said there is an "enormous possibility" that images are authentic. A proof-of-life photograph released immediately after their kidnapping showed them chained and padlocked by the neck.